Thread severing mechanism for sewing machines



\ July 22, 1947.

J. GALKIN 2,424,391

THREAD SEVERING MECHANISM FOR SEWING MACHINES I Filed Sept. 7. 1946 3 Sheets-Sheet 2 "limb,

FIG.3

JOSEPH GALKIN ci INVENTQR.'

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. ATTQRNEY Jruly22,1947. GALKlN' 2,424,391

THREAD SEVERING MECHANISM FO'H SEWING MACHINES Filed Sept. 7, 1946 4 3 Sheets-Sheet `3 l JOSEPH GALKI'Nv 13 INVENTOR.

40 ATTORNEY Patented July 22, 1947 UNITED STATES PATENT OFFICE THREAD SEVERING MECHANISM FOR SEWING MACHINES 3 Claims.

The invention relates to thread-severing devices for sewing machines for severing the chaining thread between successively stitched articles.

This invention comprises covered and concealed complemental thread-severing blades disposed crosswise of the line of seam formation, the thread-severing blades being continuously actuated during the operation of the machine.

An object of this invention is to provide an attachment particularly adapted for an overseaming sewing machine which will sever the chaining threads at the end of a sewing operation without requiring that the operator handle a pair of scissors.

Another object of this invention is to provide a thread-severing attachment fixed to the frame of the sewing machine rearwardly of the point of steam formation and including a bracket having a hollow head positioned rearward of the feeddog, the head having a horizontal groove lower than the upper surface of the head and positioned in alinement with the line of seam formation and of sufficient depth to permit the chaining thread to drop therein.

Another object of this invention is to provide a slidably mounted thread-severing blade coacting with a fixed cutting blade, the slidable blade being movable across the line of seam formation and adapted to sever the chaining thread and to provide spring means normally biasing the slidably mounted blade into a retracted position and a cam on the main shaft bringing the slidably mounted blade into cutting position.

Another object of this invention is to provide passage means in the head near the cutting position of the cutting blades to facilitate the removal of the cutting chips from the cutting blades.

With the above and other objects in view, the invention will be hereinafter more particularly described, and the combination and arrangement of parts will be shown in the accompanying drawings and pointed out in the claims which form part of this specification.

Reference will now be had to the drawings, wherein like numerals of reference designate corresponding parts throughout the several views, in which:

Figure 1 is an end view of an overseaming sewing machine, having the attachment applied thereto.

Figure 2 is a plan View of the attachment.

Figure 3 is an end view of the attachment, with the slidably mounted blade in retracted position.

Figure 4 is an end View similar to that shown 2 in Figure 3, with the slidably mounted blade in cutting position.

Figure 5 is a cross-sectional view of the attachment, the section being taken as on line 5--5 in Figure 2 and showing the blades in cutting position.

Figure 6 is an end view of the attachment, in combination with a portion of the sewing machine,v showing a cam for operating the slidably mounted blade.

Figure 7 is a plan view showing the attachment in operating position with the needle-plate of the sewing machine.

Figure 8 is a fragmentary front View of the attachment, the lever and the slidable blade being removed. Y

Figure 9 is a plan view of a flxed blade.

In the illustrated embodiment of the invention the numeral IIJ indicates an overseaming machine comprising a, curved eye-pointed oscillatory needle I I, a frame I2, and a needle plate I3. The feeding mechanism includes a feed-dog I 4, adapted to be actuated by eccentrically driven members mounted on a main shaft I5, as is well known in the sewing machine art.

The trimming attachment I6 comprises an elongated bracket I'! having an aperture IB. As shown in Figure 1, a screw I9 passing through the aperture I8 in the bracket Il secures the trimming attachment I6 to a horizontal portion 20 of the frame I2. A dowel pin 2I fixed in the bracket I1 aligns the bracket.

The trimming attachment I6 is positioned rearward of the feed-dog I4. The free end portion of the bracket I'I adjoins the feed-dog I4 and terminates in a head member 22, which is of generally rectangular form. The head member 22 has a groove 23 with a semi-circular bottom. The upper face of the head member 22 is positioned above the upper surface of the bracket I I and above the upper surface of the needle plate I3. The groove 23 is positioned in alinement with the line of seam formation of the sewing machine.

The head member 22 comprises a fixed blade 24 which is secured in the head member 22 by screws 26 threaded in the head member 22. As shown in Figure 2, the Xed blade 24 has a cut out portion 21 in alinement with the groove 23 and a bevelled cutting edge 24.

The head member 22 terminates at its lower elevation in an arm 3l having a threaded aperture 32 for a screw 33. In the head member 22 is a cavity 34 of shallowv depth and of circular cross-section for partially supporting a coil spring 35.

Coacting with the head member 22 is a hollow head member 22 having a recess 31 for a slidable blade 25 having a bevelled cutting edge 25.

The head member 22 has a cavity 38 of circular cross-section which provides the remainder portion to the cavity 34 for the spring 35. The head member 22 has a slot 39 in which a lever 40 is movably mounted and actuates the movable blade 25. The lever 4S is pivoted on the screw 33.

The head member 22 has a laterally extending free edge portion 42 which covers the recess 31 and this serves to guide the fabric out of the field of movement of the slidably mountedl The fabric passes over the cutting blade 25. blades without being damaged thereby.`

The upper surface 42 of the head member 2'2 is considerably higher than the upper surface of the needle plate I3 in order to facilitate the dropping of the chaining thread into the groove 23.

The fabric being stitched moves over the upper surface 42 of the head member 22 and when the finished end of the fabric reaches the front of the head, the chaining thread drops down into the groove 23. The chaining thread then lies within the field of movement of the slidably mounted blade 25 and is severed.

For the purpose of actuating the slidably mounted blade 25 I provide an open face type cam 45 which is suitably secured at' one end of the main shaft l5. The cam imparts cutting movements to the slidable blade under all conditions of stitch formation. One end of the coil spring 35 reacts against the rear wall of the cavity 3l while the other end of the spring presses against the slidable blade 25. The spring serves to normally bring the slidably mounted blade into a retracted position while the cam brings the slidably mounted blade into cutting position. It is to be noted that the cam 45 has a threaded boss i3 which serves similar to a threaded nut for engaging a thread on the shaft'l5.

In order to coordinate the movement of the garment sections successively into proper severving position, I provide a vertical edge guide wall dit at the rear of the head against which the superposed edge portions of the fabric sections abut while being sewed.

It is to be noted that the chain thread sewing machine herewith shown is shown only for illustration and that my invention is applicable to many other chain thread sewing machines.

It is also to be noted that while in the sewing machine herewith disclosed, the thread severing device is driven from a cam' on the main shaft, that the device may be driven from other movable members available on different sewing machines.

A's shown in Figure 5, I have provided a through opening 50 in the vertical edge guide wall 44 in alinement with the cutting blades. The opening 50 provides passage means in the head at the cutting position of the cutting blades which causes automatic removal of the cutting chips from the cutting blades and maintains the blades in proper operating condition.

In accordance with the patent statutes I have described and illustrated the preferred embodiment of my invention, but it will be understood that various changes and modifications can be made therein without departing from the spirit of the invention as defined by the appended claims.

I claim:

1. In a sewing machine of the class described, comprising a frame, a main shaft, a needle-plate and a feed-dog; a thread severing attachment fixed to said frame rearwardly of the point of seam formation for severing the chaining thread between successively stitched articles, including a bracket having a hollow head positioned rearward of said feed-dog, said head having a horizontal groove positioned in alinement with the line of seam formation and of a depth permitting said chaining thread to drop therein, a cutting blade fixed in said head and having a cut-out portion in alinement with said groove, a threadcutting blade slidably mounted in said head and coacting with said fixed cutting blade, said slidable cutting blade being movable across the line of seam formation into cutting engagement with said fixed blade and adapted to sever said chaining thread, spring means normally biasing said slidably mounted blade into a retracted position, a' camon said main shaft, a lever pivotally mounted on said head and operatively associated with saidcam for bringing said slidably mounted cutting blade into cutting position, the upper portion ofA said' head having a lateral extension of a width designed to cover and conceal said slidable cutting blade and protect the articles being stitched from damage thereby.

2, In. a chain-thread sewing machine, comprising a frame, a main shaft, a needle-plate and a feed-dog; a thread severing attachment fixed to said frame for severing the chaining thread between successively stitched articles, including a bracket having a hollow head positioned rearward of said feed-dog, said head having a horizontal groove positioned inr alinement with the line of seam formation, said groove extending down to said needle-plate for said chaining thread to drop therein, afcutting blade fixed in said hollow head and having a cut-out portion in alinement with said groove, a cutting blade slidably mounted in said head and coacting with said fixed cutting blade, said slidable cutting blade being movable across the line of seam formation into cutting engagement with said fixed blade and adapted to sever said chaining thread, spring means normally biasing said slidably mounted blade into a retracted position, a cam on said main shaft, a lever pivotally mounted on said head and operatively connected With said cam for bringing said slidably mounted cutting blade into cutting position, the upper portion of said head having a lateral extension of a width designed to cover and conceal said slidable cutting blade and protect the' articles being stitched from damage thereby.

3. In a chain-thread sewing machine, comprising a frame, a main shaft, a needle-plate and a feed-dog; a thread severing attachment fixed to said frame for severing the chaining thread between successively stitched articles, including a bracket having a hollow head positioned rearward of said feed-dog, said head having a horizontal groove positioned in alinement with the line of seam formation, said groove extending down to saidneedle-plate for said chaining thread to drop therein, a cutting blade fixed in said hollow head and having a cut-out portion in alinement with said groove, a cutting blade slidably mounted in said; head and coacting with said xed cutting blade, said slidable cutting blade being movable across the line of seam formation into cutting engagement with said fixed blade andv adapted to seversaidichaining thread, spring means normally biasing said slidably mounted blade into a retractecl position, and means for bringing said slidably mounted cutting blade into cutting position, the upper portion of said head being solid and having a lateral extension of a Width designed to cover and conceal said slidable cutting blade and protect the articles being stitched from damage thereby, said head having passage means in alnemen't with said cutting blades for automatic removal 01 cutting chips therefrom.

JOSEPH GALKIN.

REFERENCES CITED The following references are of record in the 5 le of this patent:

UNITED STATES PATENTS 

